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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_33_библиотеки_им_акад_М_И_Перельмана
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pharyngeal areas are exposed to low-intensity x-ray energy. Structures
that are very dense, such as bone and teeth, tend to cast dark shadows,
whereas less dense structures, such as tongue and palate, cast less dark
shadows. Video recording the examination is crucial for later review
(Fig. 9-4).
FIGURE 9-4 Sample still lateral videofluoroscopic image demonstrating velar
position in a child.
Videofluoroscopic images are usually recorded in multiple views.
The lateral view is employed most often (Video 9-4
), and it provides a
good view of velar and posterior wall movement. It also provides a
view of the adenoid pad, cranial base angle, and cervical spine, all of
which can affect the depth of the pharynx at the level of the velum. The
lateral view does not, however, provide a view of lateral wall
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management options. Base views, frontal views (Video 9-5 ), and
oblique views such as the Towne (Video 9-6
) and Waters views may be
used, depending on the information desired from the study and the
preference of the examining clinician. The frontal view provides
information about lateral wall movement. The base, Towne, and Waters
views provide a perspective similar to that provided by endoscopy.
They can provide information about velar, lateral wall, and posterior
pharyngeal wall movement.
The success of a videofluorographic speech evaluation is influenced
by most of the same issues that affect the endoscopic speech evaluation.
The radiographic evaluation suite includes large equipment, sudden
noises, and people wearing strange-looking lead aprons over their
medical scrubs, all of which may be worrisome to small children. The
well-trained speech clinician who is skilled in working with children
will have an opportunity to apply those skills to ensure that the child
remains interested and cooperative during the evaluation.
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Instruments Used for Documenting
Speech and Tracking Change
Instrumentation is essential when measuring the acoustic and
aerodynamic characteristics of speech production. When such
measurements are obtained for an individual before and after
treatment, they become useful, objective methods for tracking change.
These measurements are described briefly here so that you will have an
idea of how these findings should be interpreted.
Acoustic Recordings
High-quality digital recordings of speech are easier than ever to obtain.
All smart phones can record good-quality audio and video, provided
recordings are obtained in a quiet environment and aention is paid to
keeping the microphone close to the speaker. All speech evaluation
facilities have the ability to record speech. As discussed in Chapter 8, it
is important to record and store a brief (2- to 3-minute) sample of the
child producing a conversational sample and a few standard phrases or
sentences. These recordings can then be used for comparison purposes
to help determine change in response to physical management, speech
therapy, or both.
Acoustic Measurements
Nasometry is an acoustic instrumental technique that estimates the
average percentage of acoustic sound transmied through the nose and
through the mouth during speech production (Fig. 9-5). One such
instrument is called a Nasometer, and the measured quantity is referred
to as “nasalance.” Nasalance is a ratio calculated by dividing the
intensity of nasal acoustic energy by the sum of the nasal and oral
acoustic energy. Nasalance measures therefore range from nearly 0
(very lile nasal resonance) to almost 100 (extreme, excessive nasal
resonance). Nasometry is most useful for tracking nasalance scores over
time in individuals who are suspected of having some degree of VPI.
These scores offer an objective means of determining whether time,
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growth, or an intervention (behavioral, surgical, or prosthetic) has had
the effect of altering oral and nasal resonance for speech.
FIGURE 9-5 The nasometer headset positioned for obtaining nasalance
measures.
Nasalance scores are obtained while the speaker repeats words or
sentences that are selected to control for the amount of nasal resonance
expected (Dalston and Seaver, 1992; Waerson et al., 1996). Sentences
such as “Look at this book with us” and “It's a story about a zoo,” from
the Zoo Passage (Fletcher, 1978), contain no nasal consonants.
Therefore, nasal resonance would be expected to be low. Normative
studies (Dalston et al., 1991; Dalston et al., 1993; Seaver et al., 1991;
Hardin et al., 1992) have shown that individuals who are perceived as
sounding very hypernasal when producing these sentences usually
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have nasalance scores higher than 30. Sentences that contain many nasal
consonants, such as “Mama made some lemon jam” or “Amanda came
from Bounding, Maine,” are normally produced with considerable
nasal resonance. Studies have shown that individuals who produce
sentences like these with too lile nasal resonance and who are
therefore hyponasal usually have nasalance scores that are lower than 50.
Nasalance measures that exceed a predetermined cutoff score are
sometimes used as evidence of VPI. Cutoff scores can be determined
after a group of listeners has perceptually rated hypernasal resonance in
a series of speech samples characterized by a wide range of nasal
resonance produced by multiple speakers (Dalston and Seaver, 1992;
Dalston et al., 1991; Hardin et al., 1992). Nasalance scores obtained from
the same speakers are then compared with the listeners' ratings. The
cutoff score is the score beyond which most listeners tend to rate nasal
resonance as excessive. Nasalance cutoff scores (for production of the
Zoo Passage) have varied across studies from 28 to 32, possibly because
of variations in regional speech differences, regional differences in
listeners' expectations, or differences in measurement details. Research
has shown that, as mean nasalance measurements exceed the “cutoff”
score by greater and greater margins, the listener's perception of
hypernasality or audible nasal emission usually becomes more severe.
Aerodynamic Assessment
Some clinicians use measurements of nasal airflow and oral air pressure
to quantify objectively the effects of VPI on the aerodynamics of speech
(Dalston et al., 1988; Dotevall et al., 2002; Hinton & Warren, 1995;
Warren & Dubois, 1964; Warren et al., 1989). Mean oral air pressure
lower than 3 cm H2O and nasal flow in excess of 300 mL/second during
production of oral pressure consonants are generally considered in the
“abnormal” range. Lower oral pressure measurements and greater
nasal flow measures usually indicate greater VP openings during oral
consonant sound production. If VP opening occurs during production
of a consonant that requires a buildup of oral air pressure for correct
production, such as /p,b,t,d,k,g/, air may escape through that opening,
thereby resulting in increased nasal airflow and reduced oral air
pressure. Based on such measures, we can infer that abnormal VP
opening occurred during the affected consonant sound. However, we
cannot always determine the reason that this is occurring, especially in
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speakers using gloal and pharyngeal substitutions that we know can
interfere with closure. When these measurements are obtained
correctly, it is possible to estimate the size of the VP opening.
Normative pressure-flow data for estimating size of the velopharyngeal
orifice are available (Andreassen et al., 1991). Those clinicians who may
be interested in normative values for children and adolescents can find
such data in Smith et al., 2003. The title of the article is somewhat
misleading because it does not contain data only on nasal sound
segments.
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How Does Instrumental Assessment
Influence Management Decisions?
Therapy Now, Physical Management Perhaps
Later
Practicing speech pathologists should view clinical reports from
instrument-based assessment with an eye toward how those findings
could influence decisions to initiate, continue, or terminate speech
therapy. If nasalance or pressure flow measures are presented,
measures described as “within normal limits” imply that the child did
not have a clinically significant problem with VPI during the test, at
least in the opinion of the examining clinicians. This could be an
encouraging finding. Assuming the test was conducted properly, the
child demonstrated an ability to achieve VP closure during the testing. In
the therapy seing, speech performance may be different. The clinician
providing speech therapy should ask the child to replicate the tasks
performed during the instrumental assessment (e.g., the child is usually
asked to repeat the syllable string “papapapapapa” during
measurement of oral air pressure) to determine whether the child's oral
and nasal resonance in that seing is consistent with the instrumental
findings.
Acoustic (e.g., nasalance) or aerodynamic findings that fall
consistently in the abnormal range are indications that physical
management is needed now or will most likely be necessary in the near
future. However, if the child is using old, learned paerns of nasal
emission, speech therapy is the answer, not physical management.
Articulation therapy may change speech behavior (Video 9-7
). Some
children (who are sensitive to failure and who may already know that
their speech tends to “fail”) may use very lile power in speech (e.g.,
reduced loudness, reduced oral movement).
We know that use of gloal stops and pharyngeal fricatives
essentially bypasses the VP system, such that instrumental studies will
be “fooled”: imaging studies will show consistent, or at least
predominant, lack of closure. The results of aerodynamic or acoustic
studies will be difficult to interpret. These patients need to learn correct
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oral articulatory placements before a good determination can be made
that physical management is needed. (Please see Chapters 11 and 12.)
Therapy and Physical Management
Physical management may be necessary even though the VP system is
not always capable of closure. If a determination has been made that
physical management is needed, therapy to foster phonological
development and the learning of oral placements may be appropriate
even before surgical or prosthetic intervention, for the reasons stated
earlier. We are talking only about phonological and articulation
therapy, not therapy aimed at “strengthening” VP closure.
Finally, physical management of VPI does not guarantee normal
speech. Some individuals continue to be hypernasal after surgical
(Video 9-8
) or prosthetic treatment. Some of these patients improve
with therapy as they learn to use their altered mechanisms more
effectively. Others may require additional physical management.
Instrumental assessment may again be needed to determine why a
persistent problem exists and what may be done about it.
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Summary
The burden that often falls on the SLP who endeavors to help a child
with a VP problem is deciding whether some “objective” assessment of
VP closure is necessary. “Objective” assessment comes in two forms:
visualization of the VP mechanism in action and assessment of the
outcomes of the performance of the VP mechanism (aerodynamic or
acoustic). Emerging technologies such as real-time magnetic resonance
imaging are exciting but remain too expensive to be useful for routine
clinical speech assessment.
Remember that meaningful evaluation of VP function in any patient
begins with the SLP's ear, and virtually all instrument-based
assessments have historically been validated by comparison with
listener-based assessments. No instrument-based assessment has its
own validity where speech assessment is concerned.
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References
References provided here do not include all published papers
relevant to this topic. We included recent works and a few older
studies that we hoped would serve as resources for the
interested reader. For a more complete list of appropriate
references regarding these and other types of instrumentation
discussed in this chapter, please refer to Peterson-Falzone SJ,
Hardin-Jones MA, Karnell MP: Cleft palate speech (4th ed). St.
Louis: Mosby, 2010; pp 315-320.
Andreassen ML, Smith BE, Guyee TW. Pressure-flow
measurements for selected oral and nasal sound segments
produced by normal adults. Cleft Palate Craniofac J. 1991;28:398–
406.
Chadha NK, Lam GO, Ludemann JP, Kozak FK. Intranasal topical
local anesthetic and decongestant for flexible nasendoscopy in
children: a randomized, double-blind, placebo-controlled trial.
JAMA Otolaryngol Head Neck Surg. 2013;139:1301–1305.
Conlin AE, McLean L. Systematic review and meta-analysis
assessing the effectiveness of local anesthetic, vasoconstrictive,
and lubricating agents in flexible fibre-optic nasolaryngoscopy. J
Otolaryngol Head Neck Surg. 2008;37:240–249.
Dalston RM, Neiman GS, Gonzalez-Landa G. Nasometric
sensitivity and specificity: a cross-dialect and cross-culture
study. Cleft Palate Craniofac J. 1993;30:285–291.
Dalston RM, Seaver EJ. Relative values of various standardized
passages in the nasometric assessment of patients with
velopharyngeal impairment. Cleft Palate J. 1992;29:17–21.
Dalston RM, Warren DW, Dalston ET. Use of nasometry as a
diagnostic tool for identifying patients with velopharyngeal
impairment. Cleft Palate Craniofac J. 1991;28:184–187.
Dalston RM, Warren DW, Morr KE, Smith LR. Intraoral pressure
and its relationship to velopharyngeal inadequacy. Cleft Palate J.
1988;25:210–219.
Dotevall H, Lohmander-Agerskov A, Ejnell H, Bake B. Perceptual
evaluation of speech and velopharyngeal function in children
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